- for the adrenaline rush of killing a difficult boss
- for having fun showing off on farm
- for the camaraderie
- for the personal challenge of learning execution (note: I spend A LOT of time on brutal arcade style games)
- for pushing my abilities on my class
- to feel progressively stronger over an expansion cycle

If you only focus on the final point, then of course you're going to be discouraged by patch/expansion cycles.

Not everyone raids just for loot, I raided back in TBC for the goal of killing bosses that were huge lore figures, the story kept me going, not to mention the feeling of raiding with a bunch of guildies/friends coming together as a team, getting past hurdles on bosses with dedication and team work, that feeling when after weeks of wiping on a new boss, finally nailing him, moving onto the next tier and being in awe of the new raid environment.

I'm living in China but registered to EU servers. I wasn't ever ready to raid until now and I can't, haha! The reasons I personally see for raiding are to push yourself. To push your item level, to push your skill level and to achieve what few folks in WoW have done. Here's hoping I can find some runs on open raid soon!